The constant threat of bacterial contamination and the associated repercussions on health have made antimicrobial solutions a ubiquitous part of commercial and residential cleaning and disinfection processes. Dilute aqueous detergents show no detectable reduction in bacterial levels on surfaces amenable to bacterial growth and proliferation in susceptible environments, such as hospitals and in residential kitchen and bath areas. On the other hand, oxidants such as aqueous hypochlorite and phenolic compositions produce substantial reductions in bacterial levels that are relatively short-lived (3 to 6 hours). This often results in recontamination due to reuse of such surfaces, requiring frequent reapplication of disinfectant. Further, relatively high concentrations of the active agent have to be incorporated in such formulations to obtain broad spectrum disinfection. These high concentrations often have undesirable side effects such as skin and eye irritation, in addition to being potentially hazardous when in contact with food. There is therefore a need for the development of new disinfecting formulations that can provide sustained broad spectrum microbial disinfection on surfaces over prolonged periods without reapplication, even after being contacted by cleaning solutions and after surface reuse. Furthermore, it is desirable to achieve disinfecting action using low levels of the antimicrobial agent that will not pose toxicity problems for the user.
The modality of action of film-forming surface sanitizers to date has been solution based, that is, the antimicrobial action is obtained by controlled release via diffusion or dissolution of the active agents into contacting aqueous or volatile solutions. Numerous examples of this type of sanitizer have been reported. Another typical variant involves hydrolysis or dissolution of the matrix containing an antimicrobial compound, thereby effecting its release into solution. High levels of preservatives, however, are also released into contacting solutions in long-term applications. In such mechanisms, a bioactive compound is covalently bound either directly to the substrate surface or to a polymeric material that forms a nondissolving surface coating. The antimicrobial compounds in such coatings exhibit greatly diminished activity, unless assisted by hydrolytic breakdown of either the bound antimicrobial or the coating itself. In either case, relatively high levels of preservative have to be released into solution in order to elicit antimicrobial action.